Unmanned, autonomous, or remote controlled underwater or undersea or subsea vehicles are often used for scientific research and commercial/defense applications for monitoring a variety of ocean properties and marine and marine vehicle activities, and other tasks. These vehicles typically propel themselves using either battery or fuel-powered motors or engines driving onboard propellers or jets. Some major disadvantages of these methods are the high cost of the batteries and motors, and the noise they emit, and the limited endurance of the vehicle due to the limitations on storage of energy. Thus, existing propulsion methods and devices have short-term endurance capabilities while at sea. Some other vehicle types, however, are configured to merely “drift” at sea within a particular oceanic current while the vehicle controls buoyancy—therefore consuming less energy than self-propelled vehicles. However, these “drifter” vehicles are not directionally controllable, and they also suffer from limited endurance capabilities at sea due to payload and “housekeeping” energy requirements.
Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.